As a device that can accurately measure a number of particulate matters (PN: Particulate Number) contained in an exhaust gas, there is a particulate number counter called as, for example, a CPC (Condensation Particle Counter).
The CPC is to grow the particulate matters until a diameter of the particulate matter becomes big by passing the particulate matters in a supersaturated alcohol (butanol or the like) atmosphere followed by discharging the grown particulate matters from a slit and to count the discharged particulate matters by means of a laser light. Conventionally, as shown in the patent document 1, there is an integrated measurement unit comprising a single casing in which the CPC, a dilution mechanism to dilute the exhaust gas and a suction pump are housed. Then the measurement unit is arranged separately from an exhaust gas pipe and the measurement unit and the exhaust gas pipe are connected by a hot hose or the like and a rare exhaust gas from the exhaust gas pipe is diluted by means of the dilution mechanism housed in the measurement unit and introduced into the CPC. As mentioned, a reason why the hot hose is used as a piping is that a particulate matter is lost because the particulate matter attaches to the piping or the piping is clogged with the particulate matters attached to the piping if a temperature of the exhaust gas drops too much prior to dilution.
Prior Art Document
Patent Document
    Patent document 1: Japan Patent laid-open number 2008-164413